I'm sure I'm going to make a flaw somewhere in this post, but I'll try to explain anyways.
Assuming that there are 4 SoF and 4 air creatures on the field:
4 SoF's cost: 4

Its effects:
50% damage increase: Skyblitz has 8

cost, and since SoF does 50% additional damage, let's say it's comparative cost is 4

. There is a downside that 4 SoFs are needed, which cost 4 cards in the deck, but since it can be used every turn instead of just once, I'll ignore that.
Ignore shield: 4 Momentums cost 4

, so let's say the comparative cost is 4

.
Evade targeting if

: Fairly difficult to compare against anything, but quintessence does have a cost of 4

per creature, with a total of 16

. However, decreasing the comparative cost is necessary due to the fact that air creatures can still be targeted with mass CC, and that SoF is prone to PC. Let's say a cost of 4

total.
So 4 SoF's effects have a total comparative cost of 12

, and therefore 3

per card. I assume I may have forgotten a few things, but even so, 1

seems too cheap.